Aluminum plating process



United States Patent 3,462,288 ALUMINUM PLATING PROCESS Donald L.Schmidt and Reinhold Hellmann, Midland,

Mich., assignors to The Dow Chemical Company, Midland, Mich., acorporation of Delaware No Drawing. Filed June 20, 1966, Ser. No.558,583 Int. Cl. C23c 3/00 U.S. Cl. 117-37 53 Claims ABSTRACT OF THEDISCLOSURE Aluminum is plated on a substrate by contacting the substratewith aluminum hydride and a decomposition catalyst. The decompositioncatalyst is a compound of a metal of Group IVb or Vb of the PeriodicTable or mixtures thereof.

This invention relates to a non-electrolytic process for the plating ofaluminum on various substrates and more particularly relates to arelatively low temperature process for the plating of metallic aluminumfrom an aluminum hydride.

It is known that metallic aluminum may be plated from aluminum hydridesby contacting such hydrides with a substrate at or above thedecomposition temperature of the aluminum hydride. Such a processusually requires a relatively high temperature to cause decomposition ofthe aluminum hydride and therefore cannot be used to plate aluminum ontomany heat sensitive substrates. It would be highly desirable, therefore,to have a process which would permit the plating of aluminum atrelatively low temperatures.

Likewise, it is known that plating processes are general in nature andcause plating over the entire exposed surface of the substrate and itwould be highly desirable to be able to plate only selected areas of asubstrate in order to produce patterns or lettering. In addition, mostknovm aluminum plating processes do not give a coating of uniformthickness on irregularly shaped objects and such a uniform coating wouldoften be highly advantageous.

It is an object of this invention to provide a nonelectrolytic processfor the plating of aluminum onto a substrate. An additional object is toprovide a relatively low temperature process for the plating of aluminumfrom aluminum hydrides which permits the plating of heat sensitivesubstrates. Another object is to provide a process for coatingpredetermined portions of a substrate to provide designs, patterns orletters thereon. A further object is to provide a process whereby anirregularly shaped substrate is coated relatively uniformly withmetallic aluminum. These and other objects and advantages of the presentprocess will become apparent from a reading of the following detaileddescription.

It has now been discovered that, in contact with certain transitionmetal catalysts, aluminum hydrides may be used to produce plating ofmetallic aluminum at temperatures substantially below the usualdecomposition temperature of such hydrides. The use of such catalystspermits the deposition of a uniform, adherent plate or coating ofmetallic aluminum, usually in the form of a bright plate, onsubstantially any substrate at relatively low temperatures and thereforeprovides the art with a novel and relatively inexpensive process foraluminum plating of even those materials, such as organic polymers,which are heat sensitive.

Substantially any normally solid material is suitable as a substrateherein. For example, metals such as iron, magnesium, brass and copper,polymers such as polyolefins, polyamides and polymeric fiuorocarbons,glass, paper, cloth, carbon and graphite, wood, ceramics and the "icelike are all plated with aluminum by the process of this invention. Thenature of the surface being plated determines to a large extend thebrightness of the aluminum plate. In general, the use of a smooth,non-porous surface such as found on most metals and some polymer filmsproduces a brighter plate than a relatively porous surface such as thoseencountered with paper or cloth. On the surfaces of some polymers suchas polyethylene, polytetrafluoroethylene, acrylonitrile-butadienestyreneterpolymers and polypropropylene, it has been found that even betteradhesion of the aluminum plate is achieved if the surface has been mademore polar, e.g. by sulfonation, corona discharge and the like, prior toplating with the aluminum.

The term aluminum hydride is used herein in its broad sense and is meantto include any hydride compound which contains at least one aluminumatom to which at least one hydrogen atom is directly bonded and includesboth the solvated and non-solvated forms of those aluminum hydridesoccurring in both forms. Included, therefore, are aluminum trihydride,the substituted aluminum hydrides such as those having the empiricalformula AlH X wherein X is a halogen, an OR group or an R group (whereinR is an alkyl, substituted alkyl, aryl or substituted aryl group) and nhas a numerical value equal to or less than 3. Also included are thecomplex aluminum hydrides such as LiAlH NaAlH Mg(AlH and the like andcomplex substituted aluminum hydrides such as those having the empiricalformula M(AlH X wherein X has the definition given above, m has anumerical value equal to or less than 4 and M is a metal or mixture ofmetals, preferably an alkali or alkaline earth metal and a has anumerical value equal to the valence of M. Of particular utility are therelatively simple aluminum hydrides containing at least two hydrogenatoms attached to the aluminimum, e.g. AlH AIH CI, AlH Br, LiAlH and thelike. Mixtures of the various aluminum hydrides may also be employed.

It is usually desirable for ease of application to employ the aluminumhydride in solvated form. Compounds known to solvate or form complexeswith the aluminum hydrides include ethers and other oxygen-containingorganic compounds, and compounds containing a functional group such as adivalent sulfur atom, or trivalent nitrogen or trivalent phosphorousatom which is capable of allowing the solvation of an aluminum hydridewith such compound. It is usually preferred that the solvate be anetherate and a wide variety of ethers containing from about 2 to about20 carbon atoms are suitable. Usually the lower aliphatic ethers such asethyl, propyl, or butyl ethers are employed but those containing anaromatic group such as methylphenyl ether, ethylphenyl ethers,propylphenyl ether or the alicyclic ethers such as tetrahydrofuran andthe like may be employed.

In general, to achieve ease and uniformity of application, any solventor mixture of solvents or suspending agents for the aluminum hydride maybe employed whcih will not react with the aluminum hydride beyond theformation of a complex or solvate. Suitable solvents include aromatichydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbonssuch as hexane, ethers, tertiary amines and the like.

If desired, such aluminum hydrides may be prepared in situsimultaneously with the plating step by employing aluminumhydride-forming reactants such as mixtures of lithium aluminum hydrideand aluminum chloride, or sodium aluminum hydride and aluminum bromide,or the like. The presence of a metal halide such as LiCl, MgCl or AlCltogether with the aluminum hydride is not detrimental to the platingreaction.

Due to the sensitivity of most aluminum hydrides to the presence ofmoist air, it is usually desirable that the application of the aluminumplate be conducted in a substantially anhydrous inert atmosphere.

In order to produce decomposition of the aluminum hydrides below theirnormal decomposition temperatures and to cause the aluminum thusproduced to form a coating or plate on the substrate, it is necessary tocontact the aluminum hydride with certain transition metal decompositioncatalysts. Transition metal decomposition catalysts useful herein arecompounds of the metals occurring in Groups IVb and Vb of the PeriodicTable. In instances where the catalyst is applied to the substrate in asolvent, it is preferable that the metal be in the form of a compoundwhich is soluble to the extent of at least 1X 10* weight percent of thesolvent employed. For example, such compounds as ZrCl NbCl VOCl VOClTiCl -2[(C H TiCl TiBr VCl Ti(OC H Cl 2( s 7)2, TiClz 2 5 2 have provedeffective. Some of the transition metal catalysts defined herein have amore pronounced effect than others in lowering the decompositiontemperature of the aluminum hydride. The chlorides, bromides andoxychlorides of titanium, niobium, vanadium and Zirconium generally seemto be more efiective than the other compounds of Group IV]; and Vbtransition metals and TiCl has been found particularly effective inachieving lower temperature decomposition of the aluminum hydrides andplating of the aluminum thus produced. If the defined catalysts are notemployed, undesirably high temperatures are required to producedecomposition of the aluminum hydride. At such elevated temperatures,even when decomposition is achieved, there is usually no aluminumcoating or plate formed thereby.

The transition metal decomposition catalyst is preferably applied to thesubstrate prior to contact with the aluminum hydride. Such decompositioncatalyst may be applied to the substrate directly as a finely dividedsolid, as a liquid solution or suspension or, where the nature of thecatalyst and the substrate permit, deposited by vapor deposition.Preferably, however, the substrate is contacted with a sufi'icientquantity of a relatively dilute solution of the catalyst to wet thesurface of the substrate. The solvent for the catalyst is then removed,e.g. by evaporation, leaving the catalyst substantially uniformlydispersed over the surface to be plated. Catalyst solutions at leastabout 1 l0- weight percent in decomposition catalyst, and preferably inconcentrations of from about 5 lO- to about 100 weight percent ofcatalyst when applied to the substrate provide sufficient catalyst toachieve plating of aluminum from an aluminum hydride at a significantlylower temperature than is possible where no catalyst is employed. It hasbeen found that uniformity of distribution of the catalyst on thesubstrate has a significant effect on both the uniformity and thicknessof the aluminum plate. It is, therefore, desirable to apply the catalystto the substrate in a manner which will assure relatively uniformdistribution.

For substrates, such as magnesium metal and some polymers, havingsurface characteristics making uniform distribution of a catalystsolution or aluminum hydride dilficult to achieve, it has been foundadvantageous to add to such solution a small amount, e.g. from about0.0001 to about 5.0 weight percent, of a wetting agent. Suitable wettingagents include, for example, stearates such as sodium or aluminumstearate or aluminum alkoxides such as aluminum isopropoxide.

Solvents for the transition metal decomposition catalysts are thosenormally liquid materials in which the catalyst is soluble to at leastthe extent of 1X 16- weight percent, which will not adversely affect thesubstrate and which will not change the anion of the catalystsufficiently to render it insoluble. Suitable solvents include non 4.-reactive solvents such as benzene, hexane, and halogenated hydrocarbons,reactive solvents such as alcohols, aldehydes, ketones, mercaptans,carboxylic acids and mineral acids, and coordinating solvents such asethers, nitriles, amides and amines.

By application of the transition metal decomposition catalyst to onlyselected areas of the substrate, it is possible to form an aluminumplate only on such selected areas. In this manner, ornamental designs,outlines, printed circuits and the like may be produced. Likewise, allor a portion of a selected substrate may be coated or plated withaluminum to enhance the ability of such surface to adhere to othermaterials. Of particular utility is the aluminum coating of glass,ceramic, metal or polymer surfaces to enhance their bonding to adhesivepolymers and copolymers such as the copolymers of ethylene and acrylicacid.

Once the desired form and quantity of decomposition catalyst is appliedto the substrate, the catalyzed substrate surface is contacted with asuitable form of aluminum hydride. In general, it is desirable to applythe aluminum hydride as a solution or suspension containing at least1x10 Weight percent, preferably from 0.1 molar to 1.0 molar or more,aluminum hydride which may be applied by dipping, spraying or othersuitable means. However, good results are also achieved by contactingthe catalyzed substrate surface with a finely divided solid aluminumhydride. Alternatively, a vapor phase deposition of aluminum may beachieved at below usual decomposition temperatures by heating analuminum hydride in close proximity to a catalyzed substrate surface.With or without the use of reduced pressure, a coating of metallicaluminum will form on the catalyzed surface.

In some applications, such as plating a vertical surface, it isdesirable to increase the viscosity of either the catalyst solution orthe aluminum hydride solution or both. Such increase in viscosity may beachieved with known gelling or thickening agents such as aluminumoctanoate or mineral oils without adversely affecting the platingreaction.

Most of the catalysts defined herein will produce plating from thealuminum hydride at room temperature in a period of time from a fewminutes to a few hours. More rapid decomposition of the catalyzedaluminum hydride to cause plating of the aluminum on a substrate may beachieved, however, by the application of sufiicient energy thereto toinitiate the deposition. For example, the aluminum hydride and catalystmay be applied to a substrate which is heated to the requiredtemperature, or a catalyzed substrate may be contacted with a heatedbath containing aluminum hydride. Alternatively, actinic light such ascold ultraviolet light may be employed or high energy radiation such aselectron bombardment may be used to produce relatively rapid aluminumplating at low temperatures, e.g. room temperature. Likewise,combinations of such forms of energy may be used. In general, once thedecomposition of the catalyzed aluminum hydride is initiated, it will beself-sustaining and will form a continuous plate without supplyingadditional energy.

The deposition temperature of aluminum catalyzed by the transition metalcatalysts defined herein will vary depending on the particular aluminumhydride employed, upon the catalyst used, to some extent, upon thecatalyst concentration and upon the type of energy'used to initiate thedecomposition of the aluminum hydride. Such deposition temperature-swill, however, be substantially lower than those required where nocatalyst is present.

The following examples are provided to further illustrate the inventionbut are not to be construed as limiting the scope thereof.

Example 1 An aluminum hydride solution was prepared in a dry nitrogenatmosphere by admixing 49 ml. of 1.0 molar lithium aluminum hydride,18.5 ml. of 0.98 molar aluminum chloride and 156 ml. of diethyl ether.After stirring,

the solution was decanted to produce a 0.3 molar solution of aluminumhydride in diethyl ether.

Various substrates were immersed in a 0.046 molar solution of TiCl indiethyl ether, dried at 100 C., cooled to room temperature, immersed inthe aluminum hydride solution prepared above and again dried at roomtemperature. Within a few minutes, a uniform, adherent aluminum coatingwas deposited on all surfaces of the substrate which had come in contactwith the catalyst solution. The following table shows the substratesemployed and type of coat obtained:

TABLE I Appearance of Substrate: aluminum coat Polyamide film (Mylar)Mirror Cellophane film Mirror Saran film Mirror Polyethylene film(surface treated by electric discharge) Mirror Glass plate MirrorFiberglass cloth Shiny Polyvinyl chloride film Mirror POrous paper sheetDull Brass strip Mirror Example 2 In a manner similar to that of Example1, a 0.3 molar solution of aluminum hydride in ether was prepared andseveral strips of Mylar film were coated with TiCl in hexane and dried.To this solution were added 3 cc. increments of a 1.2 molar AlClsolution in diethyl ether. After each addition, one of the abovecatalyzed Mylar strips was immersed in the aluminum hydride solution.Upon exposure to an ultraviolet sun lamp, decorative, aluminum film wasdeposited on the film. Each film was evaluated as to the effect ofexcess AlCl on the decorative nature of the plate.

It was found that a decorative plate could be obtained from solutionscontaining up to about 50-50 Weight ratio of AlCl to AlH Some darkcolored background streaking was noted on plates formed from solutionscontaining higher AlCl concentrations.

Example 3 In a manner similar to that of Example 2, strips of Mylar,Saran, polyethylene and glass were dipped into a 0.046 molar solution ofTiCL; in benzene. The catalyzed films were then dried and immersed in an0.30 molar aluminum hydride solution in ether. After removal from theether solution, the substrates were placed in a convective oven heatedto 110 C. A mirror-like, uniform, adhesive coating of aluminum wasproduced in from 2 to 3 seconds.

As controls, substrates of the same materials not treated with TiCl wereimmersed in the 0.3 molar aluminum hydride solution and also placed inthe convective furnace. The furnace was slowly heated from 110 C. to 250C. over a period of one hour. The organic substrates melted and gave noevidence of aluminum deposition on their surfaces. The glass substrateshowed no evidence of aluminum deposition even at 250 C.

Example 4 In a dry nitrogen atmosphere, two strips of Mylar having athickness of 0.002 inch were immersed in a 0.046 molar solution of TiCL;in diethyl ether, dried at room temperature, immersed in a diethyl ethersolution of 0.266 molar solution in aluminum hydride and 0.005 molar inaluminum isopropoxide. The films were dried at room temperature and onefilm was exposed at ambient temperature to one megarad of high energyelectron flow. A mirror-like aluminum plate was formed extremely rapidlyon this substrate.

The second strip of Mylar film, used as control, and

not exposed to ionizing radiation, showed no aluminum plating in thesame time interval.

Example 5 In a manner similar to that of Example 1, a strip of Mylarfilm having a thickness of 0.002 inch was immersed into a 0.05 molarsolution niobium pentachloride (NbCl in diethyl ether for about 5seconds, dried, immersed in a diethyl other solution 0.3 molar inaluminum hydride and about 0.005 molar in aluminum isopropoxide forabout 5 seconds and dried again. The treated film was then heated toabout C. A uniform aluminum coating having a mirror-like appearance wasalmost immediately formed on the Mylar film.

In the same manner, an aluminum plating was formed on Mylar film byimmersing the film in a 0.05 molar solution of zirconium tetrachloridein diethyl ether, drying the treated film, immersing the film in thealuminum hydride solution as above, drying the film and heating to atemperature of 80 C.

In the same manner, an aluminum plate was formed at 80 C. on Mylar filmemploying a 0.03 molar solution of titanium tetrabromide as the catalystsolution.

In the same manner, an aluminum plate was formed at C. on Mylar filmemploying a 0.05 molar solution of vanadium oxydichloride (VOCl indiethyl ether as the catalyst solution.

Example 6 A strip of Mylar was coated with a thin layer of TICL; byexposing it to vapors of TiCl Immersion of the film thus treated in 0.2molar aluminum hydride solution and subsequent heating of the film to 80C. with infrared light yielded a shiny, adherent aluminum plate.

In a related experiment, solid TiOCl was suspended in mineral oil andapplied to one side of an 0.002 inch thick Mylar film by brushing.Immersion of the film in 0.2 molar aluminum hydride solution in diethylether followed by exposure to infrared light yielded a mirror-likealuminum plate on the side of the film to which the catalyst had beenapplied. The uncatalyzed surface of the film was not plated withaluminum.

In a similar manner, solid TiCl [C H O] suspended in mineral oil andapplied with a brush to a Mylar film also gave a mirror plate only onthe catalyzed surface of the film.

Example 7 A design was drawn on a strip of Mylar film with a glass roddipped in a 0.046 molar solution of TiCl in benzene. After evaporationof the benzene, the film was immersed in a diethyl ether solution 0.2molar in aluminum hydride and 0.001 molar in aluminum isopropoxide. Thefilm was then removed from the ether solution and heated to about 80 C.under an infrared lamp for 2 minutes. At the end of this time, aluminumwas found to have plated only the area of the design originally madewith the TiCl solution.

In a similar manner, another portion of the above catalyst solution wastransferred to a Plexiglas surface with a rubber stamp. Upon immersionin an 0.3 molar aluminum hydride ether solution and exposure to infraredlight, the printed statement contained on the original rubber stamp wasrapidly formed on the Plexiglas surface in the form of shiny, adherentaluminum letters.

In a related experiment a suspension of in mineral oil was applied witha brush to a cardboard stencil over a Mylar surface. Treatment asdescribed above yielded a lettered design of metallic aluminum on thesubstrate.

Example 8 In a manner similar to that of Example 3, a strip of Mylarfilm having a thickness of 0.002 inch was immersed in a 0.3 molaraluminum hydride solution. The

film was dried at approximately 80 C. and then immersed in a 0.045 molarsolution of TiCL, in benzene. Upon heating the above treated film toabout 80 C. a mirror-like aluminum plate was formed on the substrate.

Similar experiments were conducted wherein the TiCl was added to thealuminum hydride solution. An aluminum plate was obtained on a Mylarfilm which had been dipped into the mixture of catalyst and aluminumhydride.

In each of the above experiments, controls containing no catalystproduced no aluminum plating.

Example 9 In a dry nitrogen atmosphere, a strip of Mylar film 0.002 inchin thickness was dipped into a 0.046 molar solution of TiCl in n-hexane.The treated strip of film was dried under an infrared heat lamp and thendipped into a 0.3 molar solution of aluminum dihydride isopropoxide[AlH2(l-OC3H7)], in diethyl ether. The film was held under an infraredheat lamp for several minutes to produce a temperature of about 80 C. onthe surface of the substrate. A uniform coating of aluminum was obtained on the Mylar.

In a similar manner, uniform aluminum coatings were obtained on stripsof Mylar from a 0.3 molar diethyl ether solution of isobutyl aluminumdihydride a 0.25 molar diethyl ether solution of LiAlH a 0.2 molarbenzene solution of aluminum trihydride trimethyl amine adduct [AlH N(CHand a 0.4 molar solution of AlH Cl 2 tetrahydrofuranate.

Example 10 In a dry nitrogen atmosphere, a strip of Mylar film wasimmersed in a 0.046 molar solution of TiCL; in benzene and dried atabout 80 C. A glass microscope slide was immersed in an 0.3 molarsolution of aluminum hydride Example 11 In a nitrogen filled dry boxstrips of various substrates were immersed in a solution of TiCl forabout 1 second, dried, immersed in a solution of aluminum hydride inether and then dried under various conditions. The following table showsthe solvents and concentrations employed and the results obtained.

8 Example 12 In a nitrogen filled dry box a strip of sanded magnesiummetal was immersed in a benzene solution 0.4 molar in TiCL, forapproximately 30-60 seconds, The above solution contained about 0.006weight percent of sodium stearate. The catalyzed magnesium strip wasdried, dipped in an 0.4 molar solution of aluminum hydride in diethylether and briefly dried on a hot plate at 150 C. A light coat ofmetallic aluminum was deposited on the treated magnesium surface in afew seconds.

As a control, a duplicate sample of sanded magnesium metal was treatedin an identical manner except it was not contacted with the TiClcatalyst. No coat of aluminum was formed thereon in the same time periodat 150 C.

Example 13 In a dry nitrogen atmosphere, a strip of Mylar film wasimmersed in a 0.9 molar solution of TiCl in hexane to which 20 volumepercent mineral oil had been added to increase the viscosity. Thiscatalyst solution, due to its viscosity, deposited a heavierconcentration of catalyst on the substrate than the less viscouscatalyst solutions. The treated film was dried, immersed in a 0.3 molarsolution of aluminum hydride in diethyl ether and heated to 80 C. Anunusually heavy mirror coating of aluminum was produced on the surfaceof the substrate.

Example 14 A strip of Mylar film was immersed in a 0.046 molar solutionof TiCl in diethyl ether and dried. The catalyzed surface of the filmwas dusted with a fine powder of solid aluminum trihydride etherate andthen heated to about 80 C. with an infrared lamp. A mirror-like adherentcoat of metallic aluminum was substantially uniformly deposited on thecatalyzed surface of the film.

Various modifications can be made in the present invention withoutdeparting from the spirit or scope thereof for it is understood that welimit ourselves only as defined in the appended claims.

We claim:

1. A process for the plating of aluminum from an aluminum hydride onto asubstrate which comprises: contacting an aluminum hydride and adecomposition catalyst, in the presence of each other, with a substratefor a time sufiicient to deposit metallic aluminum onto said substrate,said decomposition catalyst being selected from the group consisting ofcompounds of the metals of Groups IVb and Vb of the Periodic Table andmixtures thereof.

2. The process of claim 1 wherein the catalyzed aluminum hydride incontact with the substrate is subjected to at least sufiicient energy toinitiate the deposition of the aluminum plate.

3. The process of claim 1 wherein the aluminum hydride is a substitutedaluminum hydride.

4. The process of claim. 3 wherein the substituted TABLE II ApproximateMolar Cone, 00110., Method used to temperature of Substrate Alli;Solvent used for catalyst TiCh, M develop plate substrate (0.) Type ofcoating Mylar 0. 2 Ether 0.00018 Infrared lamp.-. 80 Mirror finish.

Do- 0. 3 EthanoL. 0. 90 do 80 Do. Do. 0. 3 Isopropanol 0. 90 do 80 Do.Do 0.3 Carbon tetrachloride 0.90 do 80 Do. Do 0. 3 Methylene chloride 0.90 do 80 Do. Polypropylene (sulfonated) 0. 25 Heptane 0. 045 Convectivefurnace- Do. .Aerylonitrile-butadiene-styrene 0.30 Hexane--. 0. 045Infrared lamp D1111.

terpolymer. Teflon (treated with sodium 0. 20 Ether 80 Less shiny.

diphenyl). Wood 0.25 o 80 Dull. Cotton. 0.20 Benzene- 80 Do. Ny 1 0.20.do 80 Less shiny. Animal hair 0. 40 do 80 Dull.

1 0.005 M in aluminum isopropoxide.

aluminum hydride contains two hydrogen atoms bonded directly to thealuminum.

5. The process of claim 1 wherein the aluminum hydroxide is a complexaluminum hydride.

6. The process of claim 1 wherein the aluminum hydride is LiAlH 7. Theprocess of claim 1 wherein the aluminum hydride is a solvated aluminumtrihydride.

8. The process of claim 1 wherein the aluminum hydride is a compoundhaving the empirical formula of a solvated aluminum chlorodihydride.

9. The process of claim 1 wherein the decomposition catalyst is a memberselected from the group consisting of ZrCl NbCl VOCl V001 TiCl -2[(C HO], TiCl TiBr V01 Ti(OC H Cl TiCl (i-OC H TiCl -2[(C H O], Ti(BH -2[(C HO] and mixtures thereof.

10. The process of claim 1 wherein the decomposition catalyst is TiCl11. The process of claim 2 wherein the energy to initiate the depositionof metallic aluminum from the catalyzed aluminum hydride is heat.

12. The process of claim 2 wherein the energy to initiate deposition ofmetallic aluminum from the catalyzed aluminum hydride is actinic light.

13. The process of claim 2 wherein the energy to initiate deposition ofmetallic aluminum from the catalyzed aluminum hydride is high energyradiation.

14. The process of claim 1 wherein the decomposition catalyst is appliedto the substrate a sa solution containing at least 1 10- weight percentcatalyst and the aluminum hydride is applied to the catalyst-treatedsubstrate as a solution containing at least 0.0001 weight percentaluminum hydride.

15. The process of claim 1 wherein the substrate is a heat sensitivepolymer.

16. The process of claim 1 wherein the catalyst is applied to only aportion of the substrate to thereby produce a metallic aluminum design.

17. A process for the plating of aluminum from an aluminum hydride ontoa substrate which comprises applying to a substrate a decompositioncatalyst selected from the compounds of the metals of Groups Nb and Vbof the Periodic Table and mixtures thereof subsequently contacting thecatalyst-containing substrate with a solution of an aluminum hydride andmaintaining contact between the aluminum hydride and thecatalyst-containing substrate for a period suflicient to depositmetallic aluminum thereon.

18. The process of claim 17 wherein the aluminum is subjected to atleast sufiicient energy to initiate the hydride in contact with thecatalyst-treated substrate deposition of the aluminum from the aluminumhydride.

19. The process of claim 17 wherein the decomposition catalyst is amember selected from the group consisting Of ZI'C14, NbCl VOClg, VOC13,TiCl TiBr V01 Ti(OC H Cl TiCl (i-OC H TiCl -2[(C H O], Ti(BH -2[(C H O]and mixtures thereof.

20. The process of claim 17 wherein the catalyst is TiCl 21. The processof claim 17 wherein the catalyst is applied to the substrate as asolution containing at least 5 10 weight percent catalyst.

22. The process of claim 17 wherein the aluminum hydride is asubstituted aluminum hydride.

23. The process of claim 22 wherein the substituted aluminum hydridecontains two hydrogen atoms bonded directly to the aluminum.

24. The process of claim 17 wherein the aluminum hydride is solvatedaluminum trihydride.

25. The process of claim 17 wherein the aluminum hydride is a compoundhaving the empirical formula of a solvated chlorohydride.

26. The process of claim 17 wherein the aluminum hydride is a complexaluminum hydride.

27. The process of claim 17 wherein the aluminum hydride is LiAlH 28.The process of claim 17 wherein the aluminum hydride is applied as asolution in an ether containing at least 1 1O weight percent of thealuminum hydride.

29. The process of claim 18 wherein the energy to initiate thedeposition of metallic aluminum from the catalyzed aluminum hydride isheat.

30. The process of claim 18 wherein the energy to initiate thedeposition of metallic aluminum from the catalyzed aluminum hydride isactinic light.

31. The process of claim 18 wherein the energy to initiate deposition ofmetallic aluminum from the catalyzed aluminum hydride is high energyradiation.

32. The process of claim 17 wherein the substrate is a heat sensitivepolymer.

33. The process of claim 17 wherein the catalyst is applied only to aportion of the substrate to produce a metallic aluminum design.

34. The process of claim 17 wherein the aluminum hydride is applied tothe substrate as a suspension.

35. A process for the plating of aluminum from an aluminum hydride ontoa substrate which comprises (a) contacting a substrate with a solutioncontaining at least 1X10- weight percent of a catalyst selected from thegroup consisting of compounds of the metals of Groups IVb and Vb of thePeriodic Table and mixtures thereof,

(b) removing the solvent in a manner to leave the catalyst in contactwith the substrate.

(c) contacting the catalyst-containing substrate with a solutioncontaining at least 1 10- weight percent of an aluminum hydride, and

(d) applying at least sufficient energy to initiate deposition ofmetallic aluminum from the aluminum hydride.

36. The process of claim 35 wherein the aluminum hydride is asubstituted aluminum hydride.

37. The process of claim 36 wherein the substituted aluminum hydridecontains two hydrogen atoms bonded directly to the aluminum.

38. The process of claim 35 wherein the aluminum hydride is a solvatedaluminum trihydride.

39. The process of claim 35 wherein the aluminum hydride is a compoundhaving the empirical formula of a solvated aluminum chlorodihydride.

40. The process of claim 35 wherein the aluminum hydride is a complexaluminum hydride.

41. The process of claim 35 wherein the aluminum hydride is LiAlH 42.The process of claim 35 wherein the decomposition catalyst is a memberselected from the group consisting of ZI'C14, NbCl VOC12, VOC13, 2 (C2H5TiCl TiBr VCl Ti(OC H Cl TiCl (i-OC H 2 2 5)2 4)a 2 5)2 m xturesthereof.

43. The process of claim 35 wherein the decomposition catalyst is TiCl44. The process of claim 35 wherein the energy to initiate thedeposition of metallic aluminum from the catalyzed aluminum hydride isheat.

45. The process of claim 35 wherein the energy to initiate thedeposition of metallic aluminum from the catalyzed aluminum hydride isactinic light.

46. The process of claim 35 wherein the energy to initiate thedeposition of metallic aluminum from the catalyzed aluminum hydride ishigh energy radiation.

47. The process of claim 35 wherein the substrate is a heat sensitivepolymer.

48. The process of claim 35 wherein the catalyst solution is applied toonly a portion of the substrate to thereby produce a metallic aluminumdesign.

1 1 1 Z 49. The process of claim 35 wherein from about 0.0001 ReferencesCited to ahout 5 weight percent of a wetting agent is contained UNITEDSTATES PATENTS 1n elther the catalyst solution or the aluminum hydride Vsolution 3,206,326 9/1965 Whaley et al. 117107.2

50. The process of claim 49 wherein the wetting agent FOREIGN PATENTS isan aluminum alkoxide. 5

51. The process of claim 49 wherein the wetting agent 9151385 1/1963Great Bmamis aluminum isopropoxide.

52. The process of claim 49 wherein the wetting agent RALPH KENDALLPnmary Exammer is sodium stearate.

53. The process of claim 49' wherein the wetting agent 10 is aluminumstea -ate, 117-38, 47, 93.3, 107.2, 130, 138.8, 160

m g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,u62,288 Dated August 19L 1969 Inventor(s) D. L. Schmidt and R HellmannIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

In Column 9, line 4, change "hydroxide" to read --hydride--' lines 51and 52 should be interchanged.

SIGNED AND SEALED MAY 2 a 1970 (SEAL) Attest:

Edward M. Fletcher. J wmrm E. sum, m. Attesting Officer oommissioner ofPatents

